Passing extra flags through to execution in perf test isolate script.

testing/scripts/run_gtest_perf_test.py

Index: testing/scripts/run_gtest_perf_test.py
diff --git a/testing/scripts/run_gtest_perf_test.py b/testing/scripts/run_gtest_perf_test.py
index ac43ec75e0eb8327ca3a36e299b22b33b3d2b10b..5ad754e1dbc6e6cc50fd15c85db437ded9496c45 100755
--- a/testing/scripts/run_gtest_perf_test.py
+++ b/testing/scripts/run_gtest_perf_test.py
@@ -86,12 +86,15 @@ def main():
     rc = 0
     try:
       executable = rest_args[0]
+      extra_flags = []
+      if len(rest_args) > 1:
+        extra_flags = rest_args[1:]
       if IsWindows():
         executable = '.\%s.exe' % executable
       else:
         executable = './%s' % executable
       with common.temporary_file() as tempfile_path:
-        valid = (common.run_command_with_output([executable],
+        valid = (common.run_command_with_output([executable] + extra_flags,
             env=env, stdoutfile=tempfile_path) == 0)
 
         # Now get the correct json format from the stdout to write to the